Oxygen permeable contact lenses with thick payloads

ABSTRACT

A contact lens having a cap, core, and base forming three layers to allow for the contact lens to be thick enough to accommodate a payload, while ensuring sufficient oxygenation of the wearer&#39;s eye. The cap and base are each a thin layer of gas-permeable material, each shaped to form an air gap between them and the core. The two air gaps are connected by air passages that traverse the core. Oxygen from an outside environment passes through the gas-permeable cap to reach the outer air gap, through the air passages to the inner air gap, and through the gas-permeable base to reach the cornea of the wearer&#39;s eye. The cap may be annular in form, having a center hole such that the cap does not extend over the central zone of the core, reducing a thickness of the contact lens.

BACKGROUND 1. Technical Field

This disclosure generally relates to contact lenses and in particular tooxygen permeable contact lenses that carry payloads.

2. Description of Related Art

Contact lenses that provide refractive vision correction are ubiquitous.In addition, therapeutic lenses may be used to treat eye diseases andinjuries. For example, scleral contact lenses, which are supported atthe periphery of the eye, may be used to treat cornea disorders andsevere dry eye syndrome, in addition to providing refractive visioncorrection.

Due to the lack of blood vessels within the human cornea, the tissuethat makes up the cornea receives oxygen through exposure to the air. Assuch, in order to maintain corneal health, any contact lens disposedover the cornea requires at least a threshold amount of oxygenpermeability to allow for sufficient oxygenation of the cornea.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure have other advantages and features whichwill be more readily apparent from the following detailed descriptionand the appended claims, when taken in conjunction with the examples inthe accompanying drawings, in which:

FIG. 1 shows a cross sectional view of a scleral contact lens mounted onan eye.

FIG. 2A is a simplified perspective view of a three layer contact lensable to accommodate a thick payload.

FIG. 2B illustrates a more detailed exploded view of the components ofthe three-layer contact lens illustrated in FIG. 2A.

FIG. 2C shows a more detailed cross-sectional view of the three-layercontact lens illustrated in FIG. 2A.

FIG. 3A shows a cross-sectional view of a three-layer contact lens.

FIG. 3B illustrates a more detailed view of region D of FIG. 3A, whichincludes the first interface between the cap and core, and secondinterface between the core and base.

FIG. 3C illustrates a more detailed view of region E of FIG. 3A, whichincludes the central interface connecting the cap to the core of thecontact lens.

FIG. 4A shows a cross-sectional view of a three-layer contact lenshaving another structural interface between the cap, core, and base of acontact lens.

FIG. 4B shows a more detailed view of region A of FIG. 4A, containingthe glue interface.

FIG. 5 illustrates a top down view of a contact lens, where the cap isdivided into a plurality of separate cap pieces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The figures and the following description relate to preferredembodiments by way of illustration only. It should be noted that fromthe following discussion, alternative embodiments of the structures andmethods disclosed herein will be readily recognized as viablealternatives that may be employed without departing from the principlesof what is claimed.

A contact lens may carry a payload for performing various functions. Forexample, an electronic contact lens may contain a payload of one or moreelectronic components, such as an imaging device, one or more sensors,etc. The contact lens must have a sufficient thickness to accommodatethe payload. However, a greater contact lens thickness may result in areduction of the amount of oxygen that can be transmitted through thematerial of the contact lens to reach the cornea in comparison tothinner contact lenses.

In order to ensure sufficient corneal oxygenation, a contact lens may beconstructed in three layers, for example as shown in greater detail inFIG. 2. The middle structure may contain a payload(s) and is referred toas the core. The outward-facing (i.e., facing the external environment)surface of the core is covered at least partially by an outer structure,which is referred to as the cap. An inner structure, referred to as thebase, is positioned between the core and the eye. When worn by a wearer,the cap faces the outside environment, while the base is proximate to anouter surface of the wearer's eye. The cap and base are each a thinlayer of gas-permeable material, each shaped to form an air gap betweenthem and the core. The two air gaps are connected by one or more airpassages that traverse the core. Oxygen from the outside environmentpasses through the gas-permeable cap to reach the outer air gap formedbetween the cap and the core, through the air passages to the inner airgap formed between the core and the base, and through the gas-permeablebase to reach the cornea of the wearer's eye.

The cap is shaped so that it lies entirely outside a central zone of thecontact lens. For example, the cap may have an annular shape that coversonly areas in the peripheral zones of the core, instead of a dome shapethat covers both the central zone and peripheral zones of the core. As aresult, the total thickness of the contact lens is reduced compared todesigns in which the cap extends over the central zone of the contactlens, because the extra thickness of the cap is not included as part ofthe thickness of the contact lens over the central zone. In addition, byshaping the cap such that it lies entirely outside the central zone, anumber of boundaries between different materials that light may need topass through en route to the wearer's eye in comparison to if the capwas formed to cover the central zone. As such, light passing through thecontact lens to reach the wearer's eye does not pass through boundariesbetween the cap, air gap, and core, eliminating potential opticalreflection or scattering that may occur at such boundaries. Furthermore,an annular cap may be easier to support than one that extends over theentire center area of the contact lens (e.g., dome-shaped cap), and maybe less prone to breakage or cracking. Thus, the cap can be thinnerwhile still maintaining structural integrity, potentially increasing theoxygen transmission through the cap.

In some embodiments, the cap, core and base parts are fabricatedseparately, and assembled together using an adhesive. One or moreinterfaces may be formed on these parts in order to ensure properalignment and a reliable adhesive bond line for assembling the partstogether. For example, the cap may be aligned with the core at analignment stop surface. The cap includes a protrusion that displacesglue deposited in a recess formed in the core. The displacement forms acontrolled thickness bond line of glue on one side of the protrusionwhile some glue flows just to an outer surface of the contact lensthrough capillary action. This allows for the parts to be assembledtogether without the glue overflowing if more than an ideal amount ofglue is deposited.

FIG. 1 shows a cross sectional view of an example scleral contact lensmounted on an eye. Scleral contact lenses are designed to not move onthe cornea of the wearer's eye, but the contact lens does not have to bescleral. The eye 102 includes a cornea 104 and a sclera 106. The contactlens 110 is designed to contact the sclera 106 and to form a tear fluidlayer 108 over the cornea 104. The tear fluid layer may have a thicknessof about 10 um to about 200 um over the cornea. Oxygen permeates throughthe contact lens 110 and tear fluid layer 108 to the cornea 104, at arate depending upon the geometry of the contact lens 110 and the oxygentransmissibility and thicknesses of the materials that form the contactlens 110.

The contact lens 110 contains payload(s) that may include activeelectronics. As used herein, “active” electronics may refer toelectronic components capable of manipulating a signal based upon acontrol signal, and may include components containing transistors orintegrated circuits. The active payloads may include active electronics114 located within a central zone of the contact lens 110, as well asactive electronics 112 located outside the central zone. As an example,the payloads may include a femtoprojector 114 that projects images ontothe wearer's retina and corresponding electronics 112 to operate thefemtoprojector. Other payloads may include passive devices (e.g.,inactive electronics), such as a coil or antenna for wireless power ordata transmission.

As used herein, the central zone of the contact lens 110 refers to aportion of the contact lens 110 that is within a certain distance of theoptical axis of the eye 102. Conceptually, the size of the central zonemay be based on the size of the optical aperture of the eye, asprojected onto the contact lens 110, such that light rays that passthrough or originate from within the central zone of the contact lensalso pass through the optical aperture of the eye and contribute toimage formation on the retina. On the other hand, light rays fromoutside the central zone of the contact lens are blocked from enteringthe optical aperture of the eye and reaching the retina. For example,the femtoprojector 114 is located within the central zone and so is ableto project light onto the retina of the eye 102. In some embodiments,the femtoprojector 114 is located near the center of the central zone inorder to project towards a center of the retina of the eye 102 (e.g., asillustrated in FIG. 1). However, in other embodiments, thefemtoprojector 114 may be located near an edge of the central zone inorder to project towards a peripheral portion of the retina of the eye102. In addition, payload components of the contact lens 110 notintended to project light towards the eye 102 may be located outside thecentral zone of the contact lens 110, in order to prevent the componentsfrom blocking light from reaching the retina.

However, defining the central zone of the contact lens 110 in this waywould result in different size central zones for different people due tovariations in eye dimension, for different lighting conditions due tochanging of the pupil size, and for different fields of view due tooff-axis rays. As a result, the central zone may be defined as the areaof the contact lens that is within a specified distance of the opticalaxis, where the distance is selected based on the concepts describedabove. In some embodiments, the central zone is an 8 mm diameter centralzone. The diameter of the central zone is typically 2-8 mm.

On the other hand, the portion of the contact lens 110 that rests on thesclera 106 is outside the central zone, and the wearer's view of theoutside world is not affected if that part of the lens is opaque orlight-blocking. In addition, in some cases, the central zone is smallerthan the cornea 104. As such, portions of the contact lens 110 that areoutside the central zone (hereinafter referred to as the “peripheralzone” of the contact lens) may still laterally overlap the cornea 104.

The contact lens 110 has an outer surface 124 and an inner surface 122.As used herein with respect to the contact lens, terms such as “outer”“over” “top” “up” and “anterior” refer to the direction away from thewearer's eye, while “inner” “under” “bottom” “down” and “posterior”refer to the direction towards the wearer's eye.

As an example, a contact lens may be constructed from a rigid gaspermeable material having an oxygen permeability of approximately

${{Dk} \cong {100 \times 10^{- 11}( \frac{{cm}^{2}}{\sec} )( \frac{{ml}_{O_{2}}}{ml} )( \frac{1}{{mm}\;{Hg}} )}},$commonly quoted as Dk=“100”, wherein D corresponds to a diffusionconstant measured in

$( \frac{{cm}^{2}}{\sec} ),$and k corresponds to a concentration of O₂ per unit of O₂ partialpressure, and is measured in

$( \frac{{ml}_{O_{2}}}{ml} ){( \frac{1}{{mm}\;{Hg}} ).}$As such, a 200 um thickness of this material has oxygen transmissibility

${{{Dk}\text{/}t} \cong {50 \times 10^{- 9}( \frac{cm}{\sec} )( \frac{{ml}_{O_{2}}}{ml} )( \frac{1}{{mm}\;{Hg}} )}},$commonly quoted as Dk/t=“50”, wherein t corresponds to a thickness ofthe material. Generally, an oxygen transmissibility of Dk/t=“24” is theminimum recommended for daily wear contact lenses, while an oxygentransmissibility of Dk/t=“87” is the minimum recommended for extendedwear lenses in contact with the cornea. See, e.g., Holden and Mertz,Investigative Ophthalmology and Visual Science 25:1161-1167, 1984. Dkcan be measured in Barrers, where

${{1\mspace{14mu}{Barrer}} = {{10^{- 10}\frac{{cm}_{STP}^{3} \cdot {cm}}{{{cm}^{2} \cdot \sec \cdot {cm}}\;{Hg}}} = {{10^{- 11}\frac{{cm}_{STP}^{3} \cdot {cm}}{{{cm}^{2} \cdot \sec \cdot {mm}}\;{Hg}}} = {10^{- 11}( \frac{{cm}_{STP}^{3}}{{cm}^{3}} )( \frac{{cm}^{2}}{\sec} )( \;\frac{1}{{mm}\;{Hg}} )}}}},$and cm_(STP) ³ refers to a number of gas molecules that would occupy aspace of 1 cubic centimeter (1 cc) at STP (standard temperature andpressure), as calculated using the ideal gas law.

In addition, scleral lenses such as the contact lens 110 illustrated inFIG. 1 create a tear pocket 108 between the contact lens 110 and thecornea 104, the oxygen transmissibility (Dk/t) of the tear pocket 108 isalso considered when determining an overall oxygen transmissibility ofthe contact lens. As such, a rigid gas permeable scleral lens made of auniform material and having a thickness greater than a few hundredmicrons may not satisfy oxygen transmission requirements. Due to theseoxygen transmission requirements, conventional scleral contact lensestypically cannot be more than 100 to 200 um in thickness. However, manytypes of payloads (e.g., active payloads containing active electronics)may require a greater thickness (e.g., 500 to 1000 um or more).

FIG. 2A is a simplified perspective view of a three layer contact lens200 able to accommodate a thick payload (e.g., greater than 500 umthick), in accordance with some embodiments. As illustrated in FIG. 2A,the contact lens 200 comprises a cap 202, a core 204, and a base 206.The cap 202 is positioned adjacent to an outer surface of the core 204,while the base 206 is positioned adjacent to an inner surface of thecore 204. Together, the cap 202, core 204, and base 206 correspond tothe three layers of the three layer contact lens 200. When worn by awearer, the base 206 is positioned adjacent to the wearer's eye (corneaand sclera) and separated from the surface of the wearer's eye by a tearlayer, while the cap 202 and portions of the core 204 are exposed to air(except when the wearer closes their eye or blinks).

The cap 202, core 204, and base 206 are shaped such that when thecontact lens 200 is assembled, an outer air gap 208 is formed betweenthe cap 202 and the core 204, and an inner air gap 210 is formed betweenthe core 204 and the base 206. Because the outer and inner air gaps 208and 210 are each entirely enclosed by their respective structures, theouter and inner air gaps are not directly exposed to the externalenvironment, preventing any debris or other contaminants from theoutside air or from the tear layer from potentially reaching the outerair gap 208 or inner air gap 210.

The cap 202 and base 206 are each relatively thin in comparison to thecore 204, and are made of materials that are permeable to oxygen such asrigid gas permeable (“RGP”) plastic. On the other hand, the core 204 issufficiently thick to accommodate a desired payload, such as afemtoprojector or one or more other types of electronic components. Thecore 204 may also be made from an oxygen permeable material such as RGP,or from an oxygen impermeable material such as poly(methyl methacrylate)(“PMMA”). Other oxygen permeable materials may be substituted for RGPand other oxygen permeable or non-permeable materials may be substitutedfor PMMA. In some embodiments, the core 204 does not contain a payload.The thickness of the core 204 may be such that a conventional sclerallens having the thickness and material of the core 204 would haveinsufficient oxygen transmission. The cap 202, core 204, and base 206are bonded to each other via an adhesive. Suitable adhesives may includeglues such as medical grade optical cement. Example glues that may beappropriate for this application include UV-curable optical adhesivesfrom Henkel Loctite.

The cap 202 has an annular shape, such that when the cap 202 is placedover the core 204, the cap 202 covers only areas within the peripheralzones of the core, while leaving the central zone of the core 204exposed to the air. For example, the cap 202 may be formed with a centerhole having a predetermined radius corresponding to a size of thecentral zone of the core 204 (e.g., 4 mm radius). As used herein,“radius” may refer to a distance along an axis orthogonal to the centralaxis 212 of the contact lens 200.

Because the cap 202 does not extend over the central zone of the core204, the cap 202 does not contribute to the total thickness of thecontact lens 200 within the central zone. This allows for the contactlens 200 to have a reduced thickness in comparison to if the contactlens 200 was constructed with a cap that extended over the central zoneof the core 204. In addition, light passing through the contact lens toreach the wearer's eye does not pass through boundaries between the cap202, the outer air gap 208, and the core 204, eliminating potentialoptical reflection or scattering that may occur at such boundaries.Furthermore, an annular cap 202 may be more durable and more easilysupported by the core 204 in comparison to one that extends over theentire central zone of the contact lens. Thus, the cap 202 can be madethinner while still maintaining structural integrity, potentiallyincreasing the oxygen transmission through the cap 202 to reach theouter air gap 208.

The cap 202 is exposed to air or separated from air by a thin tear layer(typically about 10 μm in thickness) that forms over the cap 202. Assuch, oxygen is able to diffuse from the surrounding air through the gaspermeable material of the cap 202 (and thin tear layer) to reach theouter air gap 208. The oxygen collected in the outer air gap 208 is thenable to diffuse rapidly through one or more air passages 218 (not shownin FIG. 2A) through the core 204 to traverse through the thickness ofthe core 204 to reach the inner air gap 210. From the inner air gap 210,oxygen is able to diffuse through the gas permeable material of the base206 to reach the tear fluid layer and underlying cornea of the wearer.Because the inner air gap 210 may be configured to cover a large portionof the wearer's cornea, oxygen may be substantially evenly distributedacross the wearer's cornea through the base 206.

Because oxygen diffusion through the air (such as the air of the innerand outer air gaps, as well as the air passages traversing the core 204)is roughly 100,000 times more rapid than diffusion through permeablesolids such as RGP, the oxygen transmissibility of the contact lens 200is defined primarily by the thicknesses of the cap 202 and base 206, andnot by thickness of the outer air gap 208, inner air gap 210, or thecore 204. For example, the “Dk/t” of the entire contact lens 200 may beapproximated based upon the “Dk/t” of the cap 202 and base 206overlapping the outer air gap 208 and inner air gap 210, and not on thethickness or material of the core 204. As such, the thickness andmaterial of the core 204 may be selected to be able to accommodate adesired payload and provide sufficient structural strength to supportthe payload.

FIG. 2B illustrates a more detailed exploded view of the components ofthe three-layer contact lens 200, in accordance with some embodiments.FIG. 2C shows a more detailed cross-sectional view of the three-layercontact lens 200, in accordance with some embodiments. As illustrated inFIGS. 2B and 2C, the cap 202, core 204, and base 206 are overlaid on topof each other to form the contact lens 200, and may be aligned using oneor more registration features. For example, the cap 202 may comprise afirst registration feature 212 a and a second registration feature 212 bconfigured to interface with corresponding registration features of thecore 204. In some embodiments, the first registration feature 212 acorresponds to a radius of the center hole of the cap 202, while thesecond registration feature 212 b corresponds to a peripheral radius ofthe cap 202. The base 208 may comprise a registration feature 212 cconfigured to interface with a corresponding registration feature of thecore 204.

As illustrated in FIG. 2C, the cap 202 and the core 204 are shaped todefine the outer air gap 208 between the cap 202 and core 204. Inaddition, the cap 202 and core 204 are shaped such that an outer surfaceof the cap 202 aligns with an outer surface of the core 204 in thecentral zone when the cap 202 is placed over the core 204, in order forthe collective outer surface of the contact lens 200 as defined by thecap 202 and core 204 to be substantially smooth, and not haveprotrusions or discontinuities. For example, the core 204 may have afirst thickness t1 in the central zone, and a second thickness t2 inportions of the peripheral zone that is less than the first thicknesst1. When the cap 202 is placed over the area of the peripheral zonehaving the second thickness t2, the outer surface of the cap 202 willaligns with the outer surface of the core 204 in the central zone havingthe first thickness t1. In addition, the cap 202 and the core 204 arefurther shaped such that a bottom surface of the cap 202 is spaced apartfrom an outer surface of the core 204 when the cap 202 is placed overthe core 204, creating the outer air gap 208 between the core 204 andthe cap 202.

In some embodiments, at least one of the cap 202 and the core 204 has anon-uniform thickness between the registration features 212 a/b in orderto define the outer air gap 208 between the cap 202 and the core 204.Similarly, the base 206 may have a non-uniform thickness in order todefine the inner air gap 210 between the base 206 and the core 204. Forexample, as illustrated in FIG. 2C, the inner surface of the core 204may be substantially smooth, while the thickness of the base 206 variesbetween the registration feature 212 c and the central axis of thecontact lens so as to form a space between the base 208 and the innersurface of the core 204, defining the inner air gap 210 when the base206 and core 204 are attached to each other.

In some embodiments, the core 204 comprises one or more features foraccommodating one or more payload components. For example, asillustrated in FIG. 2B, the core 204 has a through-hole 214 a within thecentral zone of the core for accommodating an electrical device such asa femtoprojector. The femtoprojector may be placed within thethrough-hole 214 a and secured using an encapsulating material, whichfunctions both to fix the position of the femtoprojector and to protectthe femtoprojector from the outside environment.

In addition, the core 204 may comprise one or more payload features 214b in a peripheral region of the core, to accommodate one or moreadditional payload components. For example, the payload feature 214 bmay be in the form of a groove formed around a circumference of the core204, having a depth sufficient for winding the power coil around thecore 204, such that the power coil does not protrude from the payloadfeature 214 b. The core 204 may further comprise additional payloadfeatures for accommodating additional payload components 216 (e.g., asillustrated in FIG. 2C), wiring or electrical connections betweenpayload components, etc.

In some embodiments, the payload feature 214 b within the peripheralregion of the core 204 is located under the outer air gap 208 when thecap 202 is placed over the core 204. In some embodiments, the payloadcomponents (e.g., power coil) within the payload features may beencapsulated in an adhesive or other material such that the componentsare not exposed to the air within the outer air gap 208. In otherembodiments, the payload components are exposed to the air within theouter air gap 208. For example, as illustrated in FIG. 2C, the payloadfeature 214 b may be located under the cap 202, such that the payload216 (e.g., a power coil) is located within the outer air gap 208. Thisenables payload components within the core to be located in theperiphery areas of the core. In some embodiments, the core 204 maycontain at least one payload component closer to the center of the core204 in comparison to the one or more air passages 218 traversing thecore, and at least one payload component further from the center thanthe one or more air passages 218.

While FIG. 2B illustrates certain payload features in the peripheryregions of the core 204 being formed on the outer surface of the core204 (e.g., payload feature 214 b), in some embodiments, one or more ofthe payload features may be formed on the inner surface of the peripheryregion of the core 204.

The air passages 218 are formed within the core 204, and traverse thethickness of the core 204 to connect the outer air gap 208 to the innerair gap 210. Because the outer air gap 208 does not extend over thecentral zone of the core 204, the air passages 218 are formed in theperipheral zones of the core 204. In some embodiments, as illustrated inFIG. 2C, the air passages 218 are oriented to be substantiallyperpendicular to the outer and inner surfaces of the core 204, andconnect laterally overlapping portions of the outer air gap 208 andinner air gap 210. As used herein, two entities may be referred to as“laterally overlapping” if they intersect a common line perpendicular tothe outer surface of the contact lens 110.

In some embodiments, each of the air passages is substantiallycylindrical in shape (e.g., having a circular cross-section). However,in other embodiments, the air passages 218 may have different shapes(e.g., different shaped cross-sections). The cross-sectional area of theair gaps 212 is configured to allow for an amount of air flow betweenthe outer and inner air gaps that is sufficient for oxygenating thecornea of the wearer's eye.

In some embodiments, the base 206 comprises one or more support features220 to provide structural support to the inner air gap 210. Because theinner air gap 210 may extend over both the central zone and peripheryareas of the core 204 in order to allow for more even distribution ofoxygen through the base 206 to reach the wearer's cornea, supportfeatures 220 within the inner air gap 210 may be useful for maintaininggap distance and overall structural integrity of the contact lens. Thesupport features 220 may comprise one or more ridges or protrusions. Forexample, as illustrated in FIGS. 2B and 2C, the support feature 220comprises a ridge protruding from the outer surface of the base 208located at a particular radius from a central axis of the base 208. Insome embodiments, the radius of the support feature 220 may be similarto the radius of the center hole of the annular cap 202. However, inorder to avoid blocking oxygen flow within the inner air gap 210, thesupport feature 220 may extend only partway through the height of theinner air gap 210 (e.g., such that air can flow over the support feature220), be discontinuous (e.g., not extending all the way around in acircle), or some combination thereof. Even if the support feature 220does not extend all the way across the inner air gap 210 to contact anopposing surface (e.g., the inner surface of the core 204), the supportfeature 220 may still function to limit an amount of deformation of thebase 206 and the inner air gap 210.

In some embodiments, instead of or in addition to support feature 220,the inner air gap 210 may contain one or more spacers (not shown), suchas plastic micro balls, cylindrical or rectangular posts, etc., placedbetween the core 204 and the base 206 to help maintain the structuralintegrity of the contact lens and maintain gap distance of the inner airgap 210. In addition, in some embodiments, the support feature 220 maybe formed as part of the inner surface of the core 204 instead of or inaddition to on the outer surface of the base 208. In some embodiments,the core 204 and/or the cap 202 may have one or more support featuresfor providing structural support for the outer air gap 208. In someembodiments, the one or more support structures may extend along aradius of the cap 202, core 204, or cap 206. In some embodiments, atleast one of the an inner surface of the cap 202 and the outer surfaceof the base 206 comprises a matrix of grooves, in which the outer orinner air gap is defined by the space between the grooves and the core204, the remaining portions of the surface of the cap or core serving assupport features.

In some embodiments, the components of the contact lens (the cap 202,core 204, and base 206) are manufactured separately and assembledtogether at a later time. For example, the cap 202, core 204, and base206 may each correspond to a prefabricated component.

By allowing for the components of the contact lens to be manufacturedseparately, different variations of one or more components can befabricated independently, and assembled with other components to createdifferent possible combinations. In some embodiments, the base 206 maybe customized to provide a desired amount of refractive correction(e.g., customized for a specific wearer, or one or a plurality ofpredetermined refractive correction amounts, etc.). For example, thethickness and inner surface of the base 206 may be adjusted to achievedifferent amounts of refractive correction. On the other hand, the cap202 and the core 204 may be manufactured as standard components. Theouter surface of the base 206 may have a predetermined common shape,allowing for the cap 202 and core 204 to be placed on different bases206 having different amounts of refractive correction. In otherembodiments, different variations of the cap 202 and core 204 may bemanufactured and assembled with the remaining components. In someembodiments, the shapes of the components may be modified by precisionmachining on a diamond lathe.

FIG. 3A shows a cross-sectional view of a three-layer contact lens, inaccordance with some embodiments. As discussed above, the componentscorresponding to the layers of the contact lens (i.e., cap, core, andbase) may be manufactured separately and connected to each other usingan adhesive material such as glue. The cap, core, and base may contacteach other at one or more glue interfaces. For example, as illustratedin FIG. 3A, a peripheral edge of the cap 202 connects to the core 204 ata first interface 302, while a central edge of the cap 202 connects tothe core 204 at the central interface 314. On the other hand, aperipheral edge of the core 204 connects to the base 206 at a secondinterface 304.

FIG. 3B illustrates a more detailed view of region D of FIG. 3A, whichincludes the first interface 302 between the cap and core, and secondinterface 304 between the core and base. FIG. 3C illustrates a moredetailed view of region E of FIG. 3A, which includes the centralinterface 314 connecting the cap to the core of the contact lens. Eachof the glue interface 302, 304, and 314 comprises features to align therespective components being connected, as well as one or more featuresfor controlling the flow of glue between the components, such that glueis prevented from overflowing from the interface onto the outer surfacesof the contact lens, even if more than an ideal amount of glue isdeposited between the components at the glue interface.

The first glue interface 302, as illustrated in FIG. 3B, comprises areservoir 306, a displacer 308, and a wick 310. The displacer 308 isformed as a convex feature (e.g., a protrusion or ridge) on the cap 202,while a corresponding concave feature (e.g., a depression or groove) isformed on the core 204. In addition, a portion of the inner surface ofthe cap 202 and a portion of the outer surface of the core 204(hereinafter, “alignment surfaces”) may function as an alignment stop312 that aligns the cap 202 to the core 204 when the cap 202 is placedover the core 204.

Prior to assembly, an amount of glue is placed into the concave featureformed on the core 204 (hereinafter referred to as the “recess”). Whenthe cap 202 is placed on the core 204, the alignment surfaces of the cap202 and the core 204 contact each other to form the alignment stop 312and radially align the cap 202 and core 204 relative to each other. Inaddition, the alignment surfaces may be shaped such that the stop 312also aligns cap 202 to the core 204 in an axial direction.

When the cap 202 and the core 204 are aligned, the displacer 308 on thecap 202 aligns with the corresponding recess on the core 204, anddisplaces glue from the recess. At least a portion of the displaced glueis drawn up the wick 310, which is formed as the narrowing gap betweenthe surfaces of the cap 202 and core 204 as the cap 202 is aligned withthe core 204. The displaced glue is drawn up the wick 310 towards a seamat the outer surfaces of the cap 202 and the core 204 through surfacetension and capillary action.

The recess is larger than the displacer 308, such that when thedisplacer 308 is positioned within the recess, a reservoir 306 is formedon a side of the displayer 308 opposite from the wick 310 to accommodateany excess glue that would otherwise flow past the seam between the cap202 and core 204. For example, the reservoir 306 of first glue interface302 illustrated in FIG. 3 may include excess space on a side of thedisplacer 308 opposite from the wick 310, allowing for any excess glueto flow in a direction opposite from and away from the wick 310. Thus,the displacer 308 may divide the glue into a first amount that flowsthrough the wick 310, and a second excess amount that remains in thereservoir 306 on the opposite side of the displacer 308 as the wick 310,ensuring that the excess glue is not pushed past the seam between thecap 202 and core 204.

The second glue interface 304 may be constructed similarly to the firstglue interface 302 as described above. For example, the second glueinterface 304 may be formed by a displacer of the core 204 being alignedwith (e.g., through corresponding alignment surfaces of the core 204 andbase 206) a corresponding recess on the base 206. When the displacer ofthe core is placed within the reservoir of the base, at least a portionof the glue within the reservoir flows into the wick formed by the gapbetween the core and base, while a remaining excess portion of the glueis pushed into a reservoir formed on an opposite side of the displaceras the wick.

As illustrated in FIG. 3A, due to the annular shape of the cap 202, thecap 202 may be attached to the core 204 via at least two different glueinterfaces (e.g., the central interface 314 and a peripheral interface(corresponding to the first interface 302 described above). In someembodiments, the displacer 308 of the central interface 314, asillustrated in FIG. 3C, is substantially wedge-shaped, having a firstsurface that serves as an alignment surface for the cap 202 for aligningwith a corresponding alignment surface of the core 204 to form thealignment stop 312, and a second surface that aligns with a secondsurface of the core 204 to form the wick 310. As illustrated in FIG. 3C,the reservoir 306 may be formed on the same side of the displacer 308 asthe wick 310. When the cap 202 is placed over the core 204, thedisplacer 308 aligns with a recess formed on the core 204, and pushesglue that has been deposited within the recess towards the wick 310 anda seam formed between the cap 202 and the core 204. In addition, anyexcess amount of glue that may have been deposited within the recessremains within the reservoir 306 formed between the displacer 308 andthe recess, preventing glue from overflowing from the seam.

While FIGS. 3B and 3C illustrate the displacer and reservoir for eachglue interface located on particular components, in other embodiments,the displacer and reservoir may be formed on different components. Forexample, in some embodiments, the reservoir of the first glue interface302 may be formed on the cap 202, and the displacer on the core 204.Which component the reservoir and displacer are formed on may be basedupon an expected orientation of the contact lens during assembly.

FIG. 4A shows a cross-sectional view of a three-layer contact lenshaving another structural interface between the cap, core, and base of acontact lens, in accordance with some embodiments. As illustrated inFIG. 4A, the cap, core, and base are positioned such that both the cap202 and the core 204 are placed on a single surface of the base 206.This allows for the cap 202, core 204, and base 206 to be assembled withone less seam on the outer surface of the contact lens, in comparison tothe configuration illustrated in FIGS. 3A and 3B.

FIG. 4B shows a more detailed view of region A of FIG. 4A, containingthe glue interface 402. At the glue interface 402, the base 206 may havean alignment surface configured to form an alignment stop 412B with thecore 204, in order to align the core 204 with the base 206. The base 206may also have formed thereon a pair of recesses into which glue can bedeposited.

Each of the cap 202 and the core 204 may have formed thereon arespective displacer 408A and 40B configured to fit into a respectiverecess of the base 206. In addition, the cap 202 and core 204 each havealignment surfaces forming an alignment stop 412A between them foraligning the cap 202 with the core 204. As such, when the core 204 isplaced over and aligned with the base 206 using the alignment stop 412B,and the cap 202 is placed over and aligned with the core 204 using thealignment stop 412A, the cap 202 will be aligned with the base 206, suchthat the displacer 408A of the cap 202 is positioned within itscorresponding recess on the base 206.

When the cap 202 and core 204 are placed over the base 206, a wick 410is formed on one side of the displacer 408A of the cap 202 by thesurfaces of the cap 202 and the base 206. A portion of the glue in therecess flows into the wick 410 through surface tension and capillaryaction. However, a remaining excess amount of glue is pushed by thedisplacer 408A into the reservoir 406A on the opposite side of thedisplacer 408A as the wick 410, allowing for the wick 410 to receiveonly an amount of glue needed to fill the seam between the cap 202 andthe base 206 without having glue flow over the seam, even if more thanan ideal amount of glue was deposited in the recess on the base 206.

The displacer 408B of the core 204 displaces the glue deposited withinthe corresponding recess on the base 206. For example, a first amount ofglue flows into the wick 410 formed between the core 204 and the base206. In addition, a second amount of excess glue is pushed by thedisplacer 408B into the reservoir 406B.

In some embodiments, the core 202, cap 204, and base 206 are shaped suchthat a gap volume 414 is formed between the core 202, cap 204, and base206. The gap volume 414 is part of the reservoir 406A and is able toreceive excess glue displaced by the displacer 408A. In addition,because the interface between the core 204 and the base 206 does notinclude a seam on the outer surface of the contact lens, the displacer408B may push excess glue into the reservoir 406B or into the gap volume414.

In some embodiments, attaching the cap 202 and core 204 onto a singlesurface of the base 206 (as illustrated in FIGS. 4A and 4B) may allowfor a greater tolerance of excess glue, due to the gap volume 414 thatcan be formed between the cap 202 and the core 204. In addition, theresulting contact lens will only have one seam on the outer surface ofthe lens (e.g., a seam between the cap 202 and the base 208, potentiallyreducing a chance for outside contaminants (e.g., dust, tear fluid,etc.) to enter the contact lens through a seam.

As such, the components of the contact lens may be connected via one ormore glue interfaces, where each glue interface comprising a protrusionthat displaces glue deposited in a recess such that a first amount ofglue flows to a seam formed between the components, and a second excessamount of glue is displaced into an excess reservoir volume, preventingoverflow of glue beyond the outer surface of the contact lens, even ifmore than an ideal amount of glue is deposited.

In some embodiments, instead of being attached using glue, thecomponents of the contact lens may be place together using a frictionfit or a snap-on fit. For example, in some embodiments, the displacer ofa first component may have one or more features configured to snap ontoone or more features within a recess on a second component, allowing forthe components to be assembled together without glue. In otherembodiments, the components of the contact lens may be attached togetherusing a laser weld or an ultrasonic bond.

Although the above figures illustrate a contact lens having a single cap202, in some embodiments, the cap 202 comprises several separate pieces.FIG. 5 illustrates a top down view of a contact lens, where the cap isdivided into a plurality of separate cap pieces, in accordance with someembodiments. For example, as illustrated in FIG. 5, the cap 202 isdivided into four separate cap pieces 202A, 202B, 202C, and 202D. Whenplaced over the core 204, each of the cap pieces 202A-202D forms aseparate outer air gap 208 between it and the core 204, each of which isconnected to the inner gap 210 via one or more air passages 218. WhileFIG. 5 illustrates a space between each of the cap pieces 202A-D, insome embodiments, the cap pieces 202A-D directly abut each other whenplaced over the core 204. In some embodiments, by forming the cap 202out of several separate pieces, an amount of stress on the cap pieces202A-D when the cap pieces 202A-D are placed over the core 204 ispotentially reduced.

The foregoing description of the embodiments of the invention has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the invention to the precise forms disclosed, butmerely illustrates different examples. It should be appreciated that thescope of the disclosure includes other embodiments not discussed indetail above. Persons skilled in the relevant art can appreciate thatmany modifications and variations are possible in light of the abovedisclosure, without departing from the spirit and scope as defined inthe appended claims. Therefore, the scope of the invention should bedetermined by the appended claims and their legal equivalents.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the inventive subject matter.It is therefore intended that the scope of the invention be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsof the invention is intended to be illustrative, but not limiting, ofthe scope of the invention, which is set forth in the following claims.

What is claimed is:
 1. A contact lens to be worn on an eye, comprising:a core having an outer surface and an inner surface, and containing oneor more electrical components; a gas-permeable cap located entirelyoutside a central zone of the contact lens and adjacent to the core'souter surface, the cap and the core's outer surface forming an outer airgap therebetween that receives oxygen from a surrounding environmentthrough the gas-permeable cap; a gas-permeable base adjacent to thecore's inner surface and disposed over the cornea of the eye, the baseand the core's inner surface forming an inner air gap therebetween thatpasses oxygen to the cornea of the eye through the gas-permeable base;and wherein the core contains a network of one or more air passagestraversing the core from the outer air gap to the inner air gap.
 2. Thecontact lens of claim 1, wherein the cap is an annular cap with a centerhole of at least 5 mm diameter.
 3. The contact lens of claim 2, whereina center portion of the core's outer surface is flush with an outersurface of the annular cap.
 4. The contact lens of claim 1, wherein thecore has a thickness such that oxygen flow through the material of thecore is not sufficient to oxygenate the cornea of the eye.
 5. Thecontact lens of claim 1, wherein the core comprises a gas-impermeablematerial.
 6. The contact lens of claim 1, wherein the one or moreelectrical components of the core includes a femtoprojector.
 7. Thecontact lens of claim 1, wherein the one or more electrical componentscomprises at least one electrical component closer to the center of thecore than the air passages traversing the core, and at least oneelectronic component farther away from the center of the core than theair passages.
 8. The contact lens of claim 1, wherein the inner andouter air gaps laterally overlap and the one or more air passages areoriented substantially perpendicular to both the inner and the outer airgaps.
 9. The contact lens of claim 1, wherein the core contains a powercoil housed within a groove formed on the outer surface of the core. 10.The contact lens of claim 9, wherein the groove is formed within theportion of the outer surface of the core covered by the cap, such thatthe cap prevents exposure of the power coil to the outer environment.11. The contact lens of claim 9, wherein the power coil is locatedwithin the outer air gap.
 12. The contact lens of claim 1, wherein atleast one of the cap and the base comprises one or more protrusionsproviding structural support to maintain the respective outer or innerair gap.
 13. The contact lens of claim 1, wherein at least one of theouter air gap and the inner air gap is formed by a matrix of grooves ona surface of the respective cap or base.
 14. The contact lens of claim1, wherein the cap, base, and core are glued together.
 15. The contactlens of claim 14, wherein a first part of the cap, core and base has arecess; a second part of the cap, core and base has a correspondingprotrusion; the first and second parts are positioned to form a seambetween the first and second parts on a first side of the protrusion;such that the first and second parts are glued together by a glue seamformed by a flow of glue by capillary action from the recess into theseam.
 16. The contact lens of claim 15, wherein the first and secondparts are further positioned to form a reservoir for receiving excessglue on a side of the protrusion opposite from the seam.
 17. The contactlens of claim 14, wherein a first part of the cap, core and base has arecess; a second part of the cap, core and base has a correspondingprotrusion; and the first part and second part are glued together by:depositing glue into the recess; and aligning the two parts, therebycausing the protrusion to displace some of the glue deposited within therecess, wherein displacement of the glue flows by capillary action fromthe recess to a seam on a first side of the protrusion, and where anexcess amount of glue remains in a reservoir formed between the twoparts on an opposite side of the protrusion.
 18. The contact lens ofclaim 14, wherein the cap is glued to the core, and the core is glued tothe base.
 19. The contact lens of claim 14, wherein the cap is glued tothe base, and the core is glued to at least one of the cap and the base.20. The contact lens of claim 1, wherein the base provides correctiveoptical power.